The invention relates to a device for increasing a selection force on a shift lever which is pivotable around a pivot axis and also around a tilt axis aligned transversely of the pivot axis, wherein the selection force is produced, upon pivoting movements of the shift lever around the tilt axis, by means of at least one lever movable against a spring and a runoff roller placed in an operative connection with the lever.
A device for the production of selection forces is described in EP 0 849 506 A1. A selection link is non-rotatably fastened to a selector shaft. A roller is arranged at the free end of the selection link, and a spring-loaded lever system acts thereon. On pivoting the shift shaft, different and defined resistances against pivoting are produced on the shift shaft by means of spring-loaded levers. The resulting selection forces are schematically described in a shift schematic. The shift schematic for a six-gear gearbox is shown. Three adjacent shift planes are provided for the shifting of the six forward gears. The reverse gear is shifted in a fourth shift plane. A shift diagram sketched in the shift schematic shows the course of the selection force in dependence on the selection path. A movement along the abscissa between the individual shift planes corresponds to pivoting the shift shaft. Selection forces are produced by means of the described device upon a movement out of the neutral position (shift plane of third and fourth gears) to the right into the shift plane of the fifth and sixth gears and furthermore on selection into the shift plane of the reverse gear. On selection into the shift plane of the reverse gear, the selection force rises abruptly and signals the selection of reverse gear to the operator. The operator is informed by the markedly rising shift force on the shift lever on selection of the shift plane of the reverse gear that he is about to engage reverse gear. The orientation of the operator as regards the position of the shift lever to the gears is thus facilitated. The signal given to the operator by the rising selection force is in particular used to warn the operator of the inadvertent changing from a shift plane for forward gears into the shift plane for reverse gear. This so-called “crash lock” acts on inadvertent selection but also on intentional selection of the shift plane of the reverse gear. The selection force is for a moment substantially higher than the forces occurring at the shift knob on selection of the shift planes for forward gears. After the increased selection force is overcome, the actuating force decreases again to a normal level.
It is disadvantageous on devices of this kind that because of the many individual parts the cost of assembly of the gearbox is relatively high.
The device for increasing the selection force is used in shift devices for shifting of gears by means of a shift lever. A respective shift plane is allocated to one or two selectively shiftable gears situated on a gearshaft. Several gears can be shifted by the shift device. A shift plane is allocated to at least one gear, or at most two gears. Each gear can be shifted only in its predetermined shift plane.
The shift lever is arranged pivotably with respect to a housing by means of a support arrangement. The support arrangement makes possible pivoting movements of the shift lever in a selection plane and in a shift plane aligned transversely of the selection plane. The shift lever is guided by a slide during the selection and shifting processes.
The shift lever is located in the selection plane in a neutral position and is pivotable in the selection plane out of the neutral position by the selection of shift planes alternatively into one of at least two inoperative positions. If the shift lever is located in one of the inoperative positions, a shift plane is selected. The shift lever is pivotable out of the inoperative position in the shift plane for shifting one of the gears. The neutral position of the shift lever is for the most part also one of the inoperative positions, from which one of two gears is selectively shiftable.
In the inoperative positions or in the neutral position of the shift lever, selector shafts are located in a middle, neutral position, in which the gears shiftable by means of the selector shafts are not shifted. The shift lever is provided with a shift finger at a free end. Each of the selector shafts has an engagement groove or a shift opening for the engagement of the shift finger. A selective engagement in one of at least two axially parallel selector shafts is performed by selection movements of the shift lever. The shift lever is movably coupled to one of the selector shafts in these positions.
Pivoting of the shift lever in the shift plane out of the inoperative position in one or other direction results in a displacement of the selector shaft coupled to the shift lever, since the shift finger acts on a side bounding the engagement groove. One of the gears allocated to the selector shaft is engaged by the displacement of the selector shaft.
The shift lever is pivotably received by means of a universal joint in a housing fixed to a vehicle. This joint or this support arrangement provides for a casing of box-like constitution. The casing receives the shift lever and is mounted for pivoting, by means of the shift lever, on the housing fixed to the vehicle, around a tilt axis aligned transversely to the pivot axis. The tilt axis is aligned with the mid-axis of alternatively one or two pivot studs. The pivot studs support the casing on the housing, pivotably in the selection plane, however not in the shifting plane. The shift lever is pivotable with the casing around the tilt axis, immovable in the casing, in the selection plane. Upon a selection movement at the shift finger, the shift lever pivoting around the tilt axis takes the casing with it. The shift finger is arranged on the shift lever on the side of the tilt axis opposite to the shift force application position (shift knob), and pivots with the shift lever in the selection plane around the tilt axis.
The support arrangement furthermore provides for support of the shift lever in the casing, pivotably around a pivot axis in the shift plane. The pivot axis runs transversely of the tilt axis. The pivot axis is simultaneously the mid-axis of a pivot stud arranged in the casing. The shift lever is supported on the casing [for pivoting] around the pivot stud in the shift plane, however not in the selection plane. The shift finger is arranged at the opposed end of the shift lever to the pivot axis and also supported in the casing pivotably around the pivot axis in the shift plane, however not in the selection plane. The pivot axis and the tilt axis are situated intersecting in a common plane.
This solution, satisfactory per se, has the disadvantage that because the shift axis and pivot axis of the shift lever are situated in one plane, limits are placed on the adjustment of shift forces and shift paths. By shift forces are to be understood the forces which are perceptible at the shift lever by the operator at the point of force application (shift knob) upon selection and shifting. At its point of force application, the shift lever covers defined paths during selection and shifting. Each further point on the lever between the point of force application and the pivot axis or tilt axis also covers paths defined by its distance from the axes. The path, for the most part in radian measure, is dependent on the distance of the shift knob to the axes. At the same pivot angle of the shift lever around the tilt axis or the pivot axis, each of the points covers the same path, independently of whether it is pivoted around the tilt axis or the pivot axis. The shift lever is often guided by a shift slide placed between the point of force application and the axes. The design of slides which save material and space is frequently subject to limitations because of the same path of the shift lever in the slide during selection and shift movements. The shift forces on the shift knob can be affected by the lever ratio of the shift lever. The lever ratio results from the distance from the knob to the axes and from the distance from the axes to the engagement of the shift finger in the engagement groove of the selector shaft. The length of the shift lever projecting into the passenger space is as a rule limited according to construction space. The length of the shift finger, starting from the intersecting axes, is dependent on the position of the elements of the internal shifting arrangements.